Radiation Protection Ch 7 Flashcards
The average energy deposited per unit length of track.
-units of kiloelectron per micron
linear energy transfer
electromagnetic radiation such as x-rays and gamma rays(short wavelength, high energy waves emitted by the nuclei of radioactive substances) this penetrating electromagnetic radiation is ionizing and interacts randomly along the length of its track
Low LET radiation
includes particles that posses substantial mass and charge. This type of radiation causes dense ionization along its length of track and is more likely to interact with biologic tissue
High LET radiation
Describes the relative capabilities of radiation with differeing LETs to produce a particular biologic reaction
Relatives Biologic Effectiveness (RBE)
when irradiated in oxygenated, or aerobic state, biologic tissues is more sensitive to radiation then when it is exposed to radiation under anoxic (without oxygen) or hypoxic (low oxygen) conditions
oxygen effect
the ratio of the radiation dose required to cause a particular biologic response of cells or organism in an oxygen-deprived environment to the radiation dose required to cause an identical response under normal oxygenated conditions
Oxygen Enhancement Ratio (OER)
biologic damage occurs as a result of ionization of atoms on master or key molecules (DNA) which can cause these molecules to become inactive or functionally altered
direct action
refers to the effects produced by reactive free radicals that are created by the interaction of radiation with water molecules
indirect action
solitary atoms or most often a combination of atoms that behave as extremely reactive single entities as a result of the presence of unpaired electrons
free radicals
single strand break- commonly occur with low LET radiation
point mutations
the loss or change of a base in the DNA chain
mutation
nondivision (nonmitotic) form of cell death that occurs when cells die without attempting division during interphase portion of the cell life cycle – programed cell death
apoptosis
exposing a cell to as little as 0.1 Gy(1 rad) of radiation just before it begins dividing can cause mitotic delay
- the failure of the cell to start dividing on time
mitotic delay
know the types of radiation that make up Low LET Radiation and high LET radiation
Low LET= x-ray and gamma rays (short wave length, high energy waves emitted by the nuclei of radioactive substances
High LET= includes particles that posses substantial mass and charge
know how free radicals influence biologic damage
dramatically increase
be able to describe how oxygen effects the biological tissues damaged by free radicals
Presence of oxygen in biologic tissues makes the damage produced by free radicals permanent.. Without oxygen damage produced by the indirect action of radiation on a biologic molecule may be repaired.
describe the indirect action of low LET radiation interacting with biologic tissue and causing damage
it causes damage to a cell primarily through an indirect action that involves the production of molecules called free radicals